import 'dart:math';

import 'package:flutter/material.dart';

void main() {
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        // This is the theme of your application.
        //
        // Try running your application with "flutter run". You'll see the
        // application has a blue toolbar. Then, without quitting the app, try
        // changing the primarySwatch below to Colors.green and then invoke
        // "hot reload" (press "r" in the console where you ran "flutter run",
        // or simply save your changes to "hot reload" in a Flutter IDE).
        // Notice that the counter didn't reset back to zero; the application
        // is not restarted.
        primarySwatch: Colors.blue,
      ),
      home: MyHomePage(title: 'Flutter Demo Home Page'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  MyHomePage({Key key, this.title}) : super(key: key);

  // This widget is the home page of your application. It is stateful, meaning
  // that it has a State object (defined below) that contains fields that affect
  // how it looks.

  // This class is the configuration for the state. It holds the values (in this
  // case the title) provided by the parent (in this case the App widget) and
  // used by the build method of the State. Fields in a Widget subclass are
  // always marked "final".

  final String title;

  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  int _counter = 0;

  int _bottomIndex = 0;

  double _defaultIconSize = 18;

  double _selectIconSiez = 20;

  List<BottomNavigationBarItem> items;

  List<Center> centers;

  Center _currentCenter;

  _MyHomePageState() {
    items = new List.from([
      new BottomNavigationBarItem(
          icon: new Image.asset(
            "icon_home_d.png",
            width: _defaultIconSize,
            height: _defaultIconSize,
          ),
          label: "home",
          activeIcon: new Image.asset(
            "icon_home_s.png",
            width: _selectIconSiez,
            height: _selectIconSiez,
          )),
      new BottomNavigationBarItem(
          icon: new Image.asset(
            "icon_store_d.png",
            width: _defaultIconSize,
            height: _defaultIconSize,
          ),
          activeIcon: new Image.asset(
            "icon_store_s.png",
            width: _selectIconSiez,
            height: _selectIconSiez,
          ),
          label: "store"),
      new BottomNavigationBarItem(
          icon: new Image.asset(
            "icon_type_d.png",
            width: _defaultIconSize,
            height: _defaultIconSize,
          ),
          activeIcon: new Image.asset(
            "icon_type_s.png",
            width: _selectIconSiez,
            height: _selectIconSiez,
          ),
          label: "type"),
      new BottomNavigationBarItem(
          icon: new Image.asset(
            "icon_mine_d.png",
            width: _defaultIconSize,
            height: _defaultIconSize,
          ),
          activeIcon: new Image.asset(
            "icon_mine_s.png",
            width: _selectIconSiez,
            height: _selectIconSiez,
          ),
          label: "mine")
    ]);

    centers = List.from([
      new Center(
        child: new Center(
          child: new Text(
            "Home Page",
            textAlign: TextAlign.center,
            style: new TextStyle(color: Colors.black, fontSize: 40),
          ),
        ),
      ),
      new Center(
        child: new Center(
          child: new Text(
            "Store Page",
            textAlign: TextAlign.center,
            style: new TextStyle(color: Colors.black, fontSize: 40),
          ),
        ),
      ),
      new Center(
        child: new Center(
          child: new Text(
            "Type Page",
            textAlign: TextAlign.center,
            style: new TextStyle(color: Colors.black, fontSize: 40),
          ),
        ),
      ),
      new Center(
        child: new Center(
          child: new Text(
            "Mine Page",
            textAlign: TextAlign.center,
            style: new TextStyle(color: Colors.black, fontSize: 40),
          ),
        ),
      ),
    ]);
    _currentCenter = centers[0];
  }

  void _incrementCounter() {
    setState(() {
      // This call to setState tells the Flutter framework that something has
      // changed in this State, which causes it to rerun the build method below
      // so that the display can reflect the updated values. If we changed
      // _counter without calling setState(), then the build method would not be
      // called again, and so nothing would appear to happen.
      _counter++;
      _bottomIndex++;
      int index = _bottomIndex % 4;
      for (var i = 0; i < items.length; i++) {}
    });
  }

  @override
  Widget build(BuildContext context) {
    // This method is rerun every time setState is called, for instance as done
    // by the _incrementCounter method above.
    //
    // The Flutter framework has been optimized to make rerunning build methods
    // fast, so that you can just rebuild anything that needs updating rather
    // than having to individually change instances of widgets.
    //
    return Scaffold(
      appBar: AppBar(
        // Here we take the value from the MyHomePage object that was created by
        // the App.build method, and use it to set our appbar title.
        title: Text(widget.title),
      ),
      body: _currentCenter,
      floatingActionButton: FloatingActionButton(
        onPressed: _incrementCounter,
        tooltip: 'Increment',
        child: Icon(Icons.add),
      ),
      // This trailing comma makes auto-formatting nicer for build methods.
      bottomNavigationBar: BottomNavigationBar(
        backgroundColor: Colors.white,
        type: BottomNavigationBarType.fixed,
        currentIndex: _bottomIndex % 4,
        items: this.items,
        onTap: (index) {
          // print("press {$index}");

          setState(() {
            print("press {$index}");
            _bottomIndex = index;
            _currentCenter = centers[index];
          });
        },
      ),
    );
  }
}
